Digital signatures of composite resource documents

ABSTRACT

An embodiment of the disclosure can receive a composite resource document containing at least one resource. An updated manifest resource can be obtained. The updated manifest resource can list all resources in the composite resource document. A set of zero or more (0 . . . N) resources can be indicated. Each indicated resource is one that is to be subtracted from the list of resources in the updated manifest resource in order to create a generated signature reference list of identified resources to be signed. A hash token can be generated using the resources identified in the generated signature reference list to form a signature hash token. The signature hash token can be encrypted with a secret key.

BACKGROUND

The present invention relates to security of resources in a dataprocessing system.

A “document” may be a convenient metaphor for representing an instanceof a web-based business transaction or collaborative business process.The document allows the end-user to save, email and digitally sign acomplete digital representation of the end user's interactions with theinformation system and the full context of those interactions. Thedocument is also a convenient metaphor for web application developers asit gives the developers a single digital asset that can be routedthrough a business process, encapsulate the full user experiencedefinition for a rich interactive application, and contain all userinput, attachments and digital signatures related to a business processtransaction. Thus, via the document metaphor, an offline or disconnectedform fill experience may be easily offered to end-users. Unresolvedchallenges exist with digital signatures for documents, which arecomposite resource documents.

BRIEF SUMMARY

An embodiment of the disclosure can receive a composite resourcedocument containing at least one resource. An updated manifest resourcecan be obtained. The updated manifest resource can list all resources inthe composite resource document. A set of zero or more (0 . . . N)resources can be indicated. Each indicated resource is one that is to besubtracted from the list of resources in the updated manifest resourcein order to create a generated signature reference list of identifiedresources to be signed. A hash token can be generated using theresources identified in the generated signature reference list to form asignature hash token. The signature hash token can be encrypted with asecret key.

An embodiment of the disclosure can receive a composite resourcedocument, containing a set of one or more (1 . . . N) resources, eachhaving a digital signature. An updated manifest resource can beobtained. The updated manifest resource can list all resources in thecomposite resource document. A hash token can be generated using theresources identified in a generated signature reference list in thedigital signature. An encrypted hash token contained within the digitalsignature can be decrypted using an obtained decryption key to form asignature hash token. Responsive to a comparison of the generated hashtoken and the signature hash token, a signature validity result cangenerated, which indicates whether the signatures of the compositeresource document are valid or not.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram of a network of data processing systemsoperable for various embodiments of the disclosure;

FIG. 2; is a block diagram of a data processing system operable forvarious embodiments of the disclosure;

FIG. 3 (Prior Art) is a block diagram of a model of an interactivedocument flow;

FIG. 4 (Prior Art) is a block diagram of a stratified layering of theinteractive document of FIG. 3;

FIG. 5 is a block diagram of composite document system in accordancewith one embodiment of the disclosure;

FIG. 6 is a block diagram of logical transition from a monolithicinteractive document to a format of a composite document, in accordancewith one embodiment of the disclosure;

FIG. 7 is a block diagram of a relationship between a compositedocument, a REST service that makes the composite document available onthe web, the web application layer, and the end-user interaction layerin accordance with embodiments of the disclosure;

FIG. 8 is a block diagram of a logical location of an XML signature inrelation to components of a composite resource document, in accordancewith embodiments of the disclosure;

FIG. 9 is a code snippet example of a manifest, in accordance withembodiments of the disclosure;

FIG. 10 is a code snippet example of the XML data in a compositeresource document template, in accordance with various embodiments ofthe disclosure;

FIG. 11 is a code snippet example of the XML data in a filled compositeresource document of FIG. 10, in accordance with various embodiments ofthe disclosure;

FIG. 12 is a code snippet example containing a composite resourcedocument signature, in accordance with various embodiments of thedisclosure;

FIG. 13 is another code snippet example of a composite resource documentsignature definition illustrating the reference list generation, inaccordance with various embodiments of the disclosure;

FIG. 14 is a code snippet example of a composite resource documentdefinition having multiple signers and illustrating a means ofspecifying the transformed resources, in accordance with variousembodiments of the disclosure;

FIG. 15 is a code snippet example of specifying a pattern to controlreference generation, in accordance with various embodiments of thedisclosure;

FIG. 16 is a code snippet example of filtering specific resources fromthe generated signature reference list, in accordance with variousembodiments of the disclosure;

FIG. 17 is a flowchart of a process of generating a digital signaturefor a composite resource in accordance with various embodiments of thedisclosure;

FIG. 18 is a flowchart of a process of validating the digital signaturefor a composite resource of FIG. 17 in accordance with variousembodiments of the disclosure; and

FIG. 19 is a flowchart of a process of generating a signature validityresult of FIG. 18 in accordance with various embodiments of thedisclosure.

DETAILED DESCRIPTION

Unresolved challenges exist with digital signatures for documents, whichare composite resource documents, as will be detailed herein. FIG. 3(Prior Art) shows a model of an interactive document flowing through abusiness process 300. The interactive document is provisioned to thevarious collaborators, such as collaborator 312 and collaborator 314.This enables the collaborators 312 and 314 to provide their input intothe document using content repository 302. Contract template 306 can beused to create proposed contract 308. Proposed contracts may be reviewedand approved by approver 316 communicating through a network such asInternet 318 using check credit service 320 and electronic fundstransfer service 322 to generate executed contract 310. Executedcontract 310 may be stored in repository 304.

With reference to FIG. 4 a logical layering of an interactive documentis presented. In essence, the “interactive document” represents a webapplication as well as the experience of the web application by aparticular user or set of users. The documents, such as executedcontract 310, tend to be organized into several logical layers 400typically comprising data layer, a business rule layer, a logical userinterface layer, and a presentational layer. Interactive document 400depicts a logically stratified approach of representing the componentsof an interactive document within a collaborative business process.Human interface 402 is an example of a logical user interface layer andpresentation layer, while business logic and dynamic validation 404represent a business rule layer.

The data layer, represented by data access and validation 406,represents underlying data often written in extensible markup language(XML) format, addressable by XML Path language (XPath), and intended toconform to an XML schema 418 of back-end transactions an informationsystem is ultimately designed to drive. A goal of the application is the“fill experience” of the data layer. The data layer may include simpleitems of data, such as data instance 408, entered by the user, likenames, dates, numbers, and amounts as well as file attachments anddigital signatures. At key points of the business process, the data canbe separated from the rest of the document and stored in databasesand/or used to drive workflow steps or completed transactions.

Business rules, logical user interface and presentation layer attach tothe data layer providing interaction services. For example, a businessrule using XML form definition language, XForms Model 416 may makecertain parts of the data relevant only when the user is of a certainage, the XForms logical user interface 414 may provide bindingmechanisms connecting the data and the business rule metadata to thepresentation layer, and the presentation layer may divide the graphicaluser experience into multiple pages using multipage XFDL 412. ExtensibleForms Description Language (XFDL) is a class of the extensible markuplanguage (XML).

A digital signature over such a document protects the data provided bythe user and also protects other layers simultaneously, thereby creatinga protected binding between the data and the application context inwhich that data was collected. The digital signature is supportedthrough security, auditability and interoperability 410 typically usingXML and XML signature 420. For example, when the user enters a datavalue “500”, the digital signature protects not just the data value“500” but also the meaning of the data value, whether that data valuemeans “Buy 500 steel beams” or “Sell 500 shares”. This applicationrequirement conforms to the W3C XML Signatures standard, whicheffectively states a conforming application should sign and validatewhat a user “sees”, rather than just the underlying data beingcollected.

In a collaborative business process, there is a complicating factor fordigital signatures. Simple digital signature applications tend to sign adocument as a complete, opaque file, colloquially, a “bucket of bits”.The signature protects the whole file, and when any modifications aremade to the file after the signature is affixed, the digital signaturebecomes invalid. However in a collaborative business process, there areoften steps of workflow performed after a first digital signature isaffixed. These workflow steps create additional information pertinent tothe full transaction. Since the document is the representation of thefull and completed business process transaction, these workflow stepsmust modify the document, which must be done without invalidating thedigital signature.

The W3C XML Signatures standard provides a solution in the form of adigital signature transform. Without use of transforms, a single XMLsignature is capable of signing any number of URI-addressable resources.Any number of these resources can be binary, so an XML signature cansign XML content as well as non-XML content. A cryptographic hash ofeach resource is placed into the XML signature, and then a set ofresource hashes is hashed and encrypted with private key material of asigner. However, the W3C XML signature standard also allows eachresource to be transformed before it is hashed. XML resources inparticular can be transformed using XPath Filter 2, which allowsportions of the XML resource to be subtracted before the hash iscalculated.

A filtering transform can also simply list what is to be signed, butthis has less security value since anything not listed could be added tothe resource without invalidating the signature. In collaborativebusiness processes, it is a known best practice to use subtractionfilters because the expression of what to subtract is also acharacterization of what the rest of the business process is allowed tomodify after the signature is affixed. Any other additions, changes ordeletions not characterized by the subtraction filter would have thedesired effect of invalidating the digital signature.

A single XML document may become less tenable over time as applicationauthors create applications with more and more pages while alsodemanding higher form throughput per server. Known solutions havedrawbacks for digitally signing an interactive document, includingrepresenting the document as a single XML file, which allows subtractionfiltering but has poor performance, and representation of the documentas a composite resource, which offers better performance and allowssubtraction filtering within each resource but does not allowsubtraction filtering of whole resources from the composite resource.The disclosure provides a solution (detailed herein) for digitalsignatures for composite resource documents, which overcomes at least aportion of the heretofore unresolved challenges with digital signaturesfor documents.

As will be appreciated by one skilled in the art, aspects of the presentinvention may be embodied as a system, method or computer programproduct. Accordingly, aspects of the present invention may take the formof an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present invention may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing. Computer program code for carrying out operations foraspects of the present invention may be written in any combination ofone or more programming languages, including an object orientedprogramming language such as Java, Smalltalk, C++ or the like andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The program codemay execute entirely on the user's computer, partly on the user'scomputer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider).

Aspects of the present invention are described below with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

Referring to the figures, FIG. 1 depicts a pictorial representation of anetwork of data processing systems in which illustrative embodiments maybe implemented. Network data processing system 100 is a network ofcomputers in which the illustrative embodiments may be implemented.Network data processing system 100 contains network 102, which is themedium used to provide communications links between various devices andcomputers connected together within network data processing system 100.Network 102 may include connections, such as wire, wirelesscommunication links, or fiber optic cables.

In the depicted example, server 104 and server 106 connect to network102 along with storage unit 108. In addition, clients 110, 112, and 114connect to network 102. Clients 110, 112, and 114 may be, for example,personal computers or network computers. In the depicted example, server104 provides data, such as boot files, operating system images, andapplications to clients 110, 112, and 114. Clients 110, 112, and 114 areclients to server 104 in this example. Network data processing system100 may include additional servers, clients, and other devices notshown.

In the depicted example, network data processing system 100 is theInternet with network 102 representing a worldwide collection ofnetworks and gateways that use the Transmission ControlProtocol/Internet Protocol (TCP/IP) suite of protocols to communicatewith one another. At the heart of the Internet is a backbone ofhigh-speed data communication lines between major nodes or hostcomputers, consisting of thousands of commercial, governmental,educational and other computer systems that route data and messages. Ofcourse, network data processing system 100 also may be implemented as anumber of different types of networks, such as for example, an intranet,a local area network (LAN), or a wide area network (WAN). FIG. 1 isintended as an example, and not as an architectural limitation for thedifferent illustrative embodiments.

Turning now to FIG. 2 a block diagram of a data processing systemoperable for various embodiments of the disclosure is presented. In thisillustrative example, data processing system 200 includes communicationsfabric 202, which provides communications between processor unit 204,memory 206, persistent storage 208, communications unit 210,input/output (I/O) unit 212, and display 214.

Processor unit 204 serves to execute instructions for software that maybe loaded into memory 206. Processor unit 204 may be a set of one ormore processors or may be a multi-processor core, depending on theparticular implementation. Further, processor unit 204 may beimplemented using one or more heterogeneous processor systems in which amain processor is present with secondary processors on a single chip. Asanother illustrative example, processor unit 204 may be a symmetricmulti-processor system containing multiple processors of the same type.

Memory 206 and persistent storage 208 are examples of storage devices216. A storage device is any piece of hardware that is capable ofstoring information, such as, for example without limitation, data,program code in functional form, and/or other suitable informationeither on a temporary basis and/or a permanent basis. Memory 206, inthese examples, may be, for example, a random access memory or any othersuitable volatile or non-volatile storage device. Persistent storage 208may take various forms depending on the particular implementation. Forexample, persistent storage 208 may contain one or more components ordevices. For example, persistent storage 208 may be a hard drive, aflash memory, a rewritable optical disk, a rewritable magnetic tape, orsome combination of the above. The media used by persistent storage 208also may be removable. For example, a removable hard drive may be usedfor persistent storage 208.

Communications unit 210, in these examples, provides for communicationswith other data processing systems or devices. In these examples,communications unit 210 is a network interface card. Communications unit210 may provide communications through the use of either or bothphysical and wireless communications links.

Input/output unit 212 allows for input and output of data with otherdevices that may be connected to data processing system 200. Forexample, input/output unit 212 may provide a connection for user inputthrough a keyboard, a mouse, and/or some other suitable input device.Further, input/output unit 212 may send output to a printer. Display 214provides a mechanism to display information to a user.

Instructions for the operating system, applications and/or programs maybe located in storage devices 216, which are in communication withprocessor unit 204 through communications fabric 202. In theseillustrative examples the instructions are in a functional form onpersistent storage 208. These instructions may be loaded into memory 206for execution by processor unit 204. The processes of the differentembodiments may be performed by processor unit 204 usingcomputer-implemented instructions, which may be located in a memory,such as memory 206.

These instructions are referred to as program code, computer usableprogram code, computer executable instructions or computer readableprogram code that may be read and executed by a processor in processorunit 204. The program code in the different embodiments may be embodiedon different physical or tangible computer readable media, such asmemory 206 or persistent storage 208.

Program code 218 is located in a functional form on computer readablemedia 220 that is selectively removable and may be loaded onto ortransferred to data processing system 200 for execution by processorunit 204. Program code 218 and computer readable media 220 form computerprogram product 222 in these examples. In one example, computer readablemedia 220 may be in a tangible form, such as, for example, an optical ormagnetic disc that is inserted or placed into a drive or other devicethat is part of persistent storage 208 for transfer onto a storagedevice, such as a hard drive that is part of persistent storage 208. Ina tangible form, computer readable media 220 also may take the form of astorage media of persistent storage, such as a hard drive, a thumbdrive, or a flash memory that is connected to data processing system200. The tangible form of computer readable media 220 is also referredto as computer recordable storage media. In some instances, computerreadable media 220 may not be removable.

Alternatively, program code 218 may be transferred to data processingsystem 200 from computer readable media 220 through a communicationslink to communications unit 210 and/or through a connection toinput/output unit 212. The communications link and/or the connection maybe physical or wireless in the illustrative examples. The computerreadable media also may take the form of non-tangible media, such ascommunications links or wireless transmissions containing the programcode.

In some illustrative embodiments, program code 218 may be downloadedover a network to persistent storage 208 from another device or dataprocessing system for use within data processing system 200. Forinstance, program code stored in a computer readable storage medium in aserver data processing system may be downloaded over a network from theserver to data processing system 200. The data processing systemproviding program code 218 may be a server computer, a client computer,or some other device capable of storing and transmitting program code218.

According to an illustrative embodiment using data processing system 200of FIG. 2 as an example, processor unit 204 executes acomputer-implemented process for creating a digital signature for acomposite resource document receives the composite resource documentcontaining at least one resource from a source including communicationsunit 210, storage devices 216 or input/output unit 212. Processor unit204 obtains an updated manifest resource, wherein the updated manifestresource lists all resources in the composite resource document, andindicates zero, one or a plurality of resources to subtract from thelist of resources in the updated manifest resource to create a generatedsignature reference list of identified resources to be signed. Processorunit 204 generates a hash token using the resources identified in thegenerated signature reference list to form a signature hash token andencrypts the signature hash token with a secret key.

Processor unit 204 further processes the computer-implemented process tovalidate a digital signature for a composite resource document.Processor unit 204 receives the composite resource document, containingone or a plurality of resources, having a digital signature from asource including communications unit 210, storage devices 216 orinput/output unit 212. Processor unit 204 obtains an updated manifestresource, wherein the updated manifest resource lists all resources inthe composite resource document. Processor unit 204 generates a hashtoken using the resources identified in a generated signature referencelist in the digital signature to form a generated hash token anddecrypts an encrypted hash token contained within the digital signatureusing an obtained decryption key to form a signature hash token.Processor unit 204 responsive to at least a comparison of the generatedhash token and the signature hash token generates a signature validityresult.

In an alternative embodiment, program code 218 of FIG. 2 containing thecomputer-implemented process may be stored within computer readablemedia 220 as computer program product 222. In another illustrativeembodiment, the process for digitally signing a composite resourcedocument may be implemented in an apparatus comprising a communicationsfabric, a memory connected to the communications fabric, wherein thememory contains computer executable program code, a communications unitconnected to the communications fabric, an input/output unit connectedto the communications fabric, a display connected to the communicationsfabric, and a processor unit connected to the communications fabric. Theprocessor unit of the apparatus executes the computer executable programcode to direct the apparatus to perform the process.

With reference to FIG. 5 a block diagram of composite document system inaccordance with one embodiment of the disclosure is presented. Compositedocument system 500 is an example of a set of components includingsupport of an underlying operating system services typical of a systemsuch as data processing system 200 of FIG. 2.

Composite document system 500 contains a number of interrelatedcomponents comprising enhanced signature generator 502, enhancedsignature metadata 504, manifest resource 506, URI resolver 508, objectelement 510 and composite document structure 512.

Enhanced signature generator 502 provides a capability for processingXML statements to generate a digital signature conforming to theapplicable XML standards used. The signature generator is enhanced tocontain URI resolver 508, which locates resources required during thecreation of the digital signature. URI resolver 508 uses universalresource identifiers to obtain specified resources included in thecomposite document. A URI inherently locates a referenced resource.Including the resolver with the signature generator allows the requiredresource entries to be found by a typical commercial XML signatureprocessor, whether the resources are located locally within thecomposite resource document or remotely on a web server. The caller ofthe digital signal library function provides URI resolvers to a digitalsignal library. The URI resolver is typically part of (provided by) aprogramming language, such as Java.

Enhanced signature metadata 504 includes additional items that can beincluded as signature properties elements. The additional items includeend user locale descriptor, local date and time of signing, and UTC dateand time of signing.

Manifest resource 506 contains a listing of all resources containedwithin the composite resource document. Typically, the processor of thecomposite resource document updates Manifest resource 506 any time aresource is added to or deleted from the composite resource document.However, for the purposes of this disclosure, it is only necessary forManifest resource 506 to reflect the resources in the composite resourcedocument at the time of generating a digital signature and at the timeof validating a digital signature. Object element 510 is a set ofelements comprising one or more elements containing special contentdesigned by an author within a signature element of the compositedocument. In the example embodiment object element 510 contains aspecially recognized XML attribute declaring a list of resourcedescriptors that indicate resources to subtract from the list ofreference elements generated into the signed information construct.

Composite document structure 512 defines a logical structure for arelative positioning of elements comprising a composite resourcedocument representing an interactive web document format. Typicalelements comprise a header, such as a mimetype identifier, resources ofwizard pages, images, form pages, data instances, attachments formatmodels, interaction controls and a manifest. FIG. 6 illustrates anexample of a composite document structure.

With reference to FIG. 6 a block diagram of logical transition from amonolithic interactive document to a format of a composite document inaccordance with one embodiment of the disclosure is presented.Structures 600 represent a logical transition that has evolved overtime. The transition does not depict a transform that occurs duringprocessing; rather the representation depicts similarities anddifferences of the different models. In the figure W represent wizardpages, F represents forms pages, D represent data instances, Mrepresents a forms model and IC represents an interaction controller.

Structure 602 represents a document as a single XML file format using amonolithic model. Structure 604 represents a resource decomposition viewof structure 602, with the addition of an optional interactioncontroller to help manage transitions among the wizard page and formpage resources comprising the interactive user interface definitionwithin Structure 602.

Structure 606 represents a compressed archive format of a compositeresource document format using the open document format (ODF) packagingformat as a compressed archive containing all resources needed for theinteractive document. The document format of structure 606 internallycontains various components of Structure 604, and hence Structure 602,as separate resources. Structure 606 also contains mimetype 608information element and a Manifest 610 resource.

The compressed archive format is accessible via an applicationprogramming interface that permits additions, deletions and changes toresources and directories, and of course the ability to get the contentof resources and directory lists. Typically, such additions, deletionsand changes to resources and directories are reflected in the content ofthe Manifest 610 resource.

With reference to FIG. 7 a block diagram of a relationship between acomposite document, a REST service that makes the composite documentavailable on the web, the web application layer, and the end-userinteraction layer in accordance with embodiments of the disclosure ispresented. In an illustrative embodiment, enablement of web-basedend-user interaction with composite documents uses a representationalstate transfer (REST) architected service front-end to the document. Theservice allows a document template to be copied and become the centralartifact of an instance of a collaborative business process. Rather thanthe whole document being transmitted through the business process, thetoken of access control to the REST interface of the instantiateddocument is passed through the business process.

Relationship 700 applies for the duration of business process 702 toprovide an association of application client layer 704 with applicationserver layer 706, document interaction layer 708 and composite webresource layer 710. The document interaction layer 708 provides theComposite resource document processor, REST interface 714 forinteracting with the logically unpacked composite resource document 712.Two endpoints in the REST interface 714 offer the ability to generate aspecified XML digital signature in the composite resource document, andvalidate a specified XML digital signature in the composite resourcedocument. Composite resource document processor, REST interface 714provides access to interact with and modify the logically unpackedcomposite resource document 712 to both server 716 and client 718logical layers.

With reference to FIG. 8, a block diagram of a logical location of anXML signature in relation to components of a composite resourcedocument, in accordance with the disclosure is presented. An exampleimplementation uses an Apache XML Signature library, (Apache is atrademark of the Apache Software Foundation), although implementationscan also use XML signature facilities built into Java. Logicalrelationship 800 for composite resource document 802 in the exampleembodiment provides a URI resolver to the XML signature generator toallow the signature generator to find the resources of the compositeresource document. Composite resource document 802 comprises logo 804,forms pages 806 and forms pages 808 with data instance 810 and datainstance 812. Data instance 812 further contains XML signature 814.

Prior to generating XML signature 814, markup of the signature appearsin the XML data of an XForms instance in the following form:

<Signature xmlns=″http://www.w3.org/2000/09/xmldsig#″> <SignedInfo><CanonicalizationMethod Algorithm=“http:// www.w3.org/TR/2001/REC-xml-c14n-20010315”/> <SignatureMethod Algorithm=“http://www.w3.org/2001/04/xmldsig-more#rsa- sha256”/> <ReferenceURI?>...</Reference> + </SignedInfo><SignatureValue>3H3K9TigFCzVDT4//wbZpAHr0wEAAA==</SignatureValue>(<KeyInfo>)? (<Object Id?>)* </Signature>

Within the SignedInfo element, an XML signature can use Referenceelements to list one or more resources to sign or validate. Theresources are indicated by a URI, which in the example implementationwere resolved by the URI resolver of the disclosure. Logicalrelationship 800 depicts a logical location of XML signature 814 withinthe data layer as well as an ability of XML signature 814 to relativelyreference resources within the composite resource document 802regardless of where the composite resource document is stored. Animplementation could use a get resource endpoint in the REST service,but the example implementation using the URI resolver directly accessesthe composite resource document because the XML signature functionalityis behind the REST interface 714 as part of the composite resourcedocument processor 714 (the implementation of the REST interface).

The XML signature generator itself then provides an ability to furtherfilter each resource using a Transforms element within the Referenceelement. Ultimately, the hash (digest) of the resource is calculated.During signature generation, the hash is stored in the DigestValueelement. During validation, the calculated hash is compared to theDigestValue to determine whether the resource has been modified (whichwould invalidate the signature). When generating a signature, once theDigestValue of each resource has been calculated and stored within theReference element, the hash of the entire containing SignedInfo element(see above) is calculated, encrypted with the signer's private key, base64 encoded and stored in the Signature Value element. During signaturevalidation, the DigestValue values are checked for equivalence withcalculated hashes of the resources at the time of validation, andprovided equality is achieved for each resource indicated by a Referenceelement, the hash of the SignedInfo is obtained and compared forequality with the base 64 decoded, decrypted hash value stored in theSignature Value element at the time of signature generation. Oninequality of any DigestValue or the Signature Value with hashescalculated during validation, an invalid result is produced. Otherwise,core validation reports a successful result, and applications are freeto perform secondary checks such as key expiry, key revocation, issuervalidity, and membership in a trusted key list.

In addition to a custom URI resolver, the disclosed process overloadsstandard behavior of the XML signature generator by separating theDigestValue calculations from the final encryption of the SignatureValue, which requires the private key material of an end user. The XMLsignature generator in the disclosed process is located on the server aspart of the REST service implementation 714. The disclosed processprovides a dummy private key to enable the XML signature generator togenerate the Signature Value. The SignedInfo generated is returned tothe client machine. The SignedInfo is hashed, and the hash is encryptedwith the private key of the user. The disclosed process provides aseparate REST endpoint within REST interface 714 enabling the setting ofthe final correct Signature Value into the digital signature. Signaturevalidation requires no similar overload since validation only requiresthe public key of the signer.

A standard XML signature system provides for signing multiple resources,and is exploited to create basic digital signatures on compositedocuments. However, digital signatures on composite documents require asubtraction filter mechanism to be secure.

Using a default configuration, an example implementation of thedisclosed process overloads the digital signature generation step forthe composite document with a preprocessing step that builds a list ofreference elements for the SignedInfo of the specified digitalsignature. In one example, a reference list may be created as follows:

{ For each resource R in the composite resource document,  if R iscontent.xml or the resource containing the digital signature markup,  do nothing  else   if there is not a Reference element for R, then  add a Reference element indicating R in the URI attribute. If theReference list contains a same document (URI=“”) Reference SD, then  Addto SD a Transform that subtracts the digital signature markup Else  Adda same document Reference (URI=“”) that subtracts the digital signaturemarkup.  }

The conditional test for pre-existence of a reference for R (in thefifth textual line above) allows the digital signature markup to expresstransforms on specific resources within the composite resource document.Any resources not specifically referenced by digital signature markupare added to the digital signature markup and are therefore signed inentirety. Thus, in a default configuration, the SignedInfo is augmentedto sign the entire composite resource document except as indicated bypre-existing references and respective possible transforms (which wouldlikely be subtraction transforms for security of the individualresources).

In an example embodiment, content.xml contains only control structuresrelated to managing page navigation and other interactions, so theexample prototype does not automatically sign the content.xml resource,although an author of the digital signature markup can sign thecontent.xml resource or any portion of it by adding a reference elementwith URI=“content.xml”. The resource containing the digital signaturemarkup is also omitted from the resources for which the exampleembodiment generates reference elements. This resource must change aspart of generating the digital signature, so the resource must behandled specially as an “enveloped” signature.

One resource within a composite resource document is Manifest 610. Thus,if any resources are added to or deleted from the composite resourcedocument after signing, then the Manifest 610 is changed such thatDigestValue of the Reference that protects the Manifest 610 will notmatch, which will produce a signature validity result of invalid. Theactual generated signature ensures no changes can be made to theresources that were present at the time of signing, except as permittedby any transforms expressed in the (signed) Reference elements. Sincethe Reference elements are signed, the only changes allowed to resourcesare those that were expressed by the author of the digital signaturemarkup in Reference Transforms that existed at the time of signaturegeneration.

The XML signature standard allows authors to include special contentwithin a signature element using an Object element. The example designuses the capability to provide an override of default behavior of theexample implementation. In the example, an Object element bearing aspecially recognized XML attribute declares a list of resourcedescriptors indicating resources to subtract from the list of Referenceelements generated into the SignedInfo. The resource descriptors allowwildcard match patterns as in the following example:

<Object compdoc:resourceFilter=“true” xmlns:compdoc=“&compDocNS;”> <compdoc:resourceDescriptorfilter=“subtract”>attachments/*</compdoc:resourceDescriptor> </Object>

By allowing subtraction of resources that match given resourcedescriptors, the disclosed mechanism enables the author of the digitalsignature markup to enable end-users to add or delete specifiedresources to or from the composite resource document after the signatureis affixed.

In the example design, the object is automatically added to the list ofReference elements of the SignedInfo and protected by the digitalsignature. The inclusion of the special Object causes the process toautomatically add a subtraction Transform to the Reference for theManifest 610 resource enabling addition and deletion of resourcesmatching resource descriptors without invalidating the hash valueproduced for the Manifest 610 resource when a digital signature isgenerated.

In addition the example design automatically writes and signs additionalinformation into the digital signature markup before signaturegeneration. Another object element is added to record basic signaturemetadata in selected SignatureProperties elements. The specific metadataitems recorded typically include an end-user (signer) locale descriptor,local date and time of signing and UTC date and time of signing. Areference to this metadata object is automatically added to theSignedInfo to protect the metadata by the digital signature.Illustrative embodiments also complete a KeyInfo element with X509Data,including the X509SubjectName and X509Certificate elements, and areference to the KeyInfo element is also added to the SignedInfo. Thesignature metadata and the KeyInfo content help to meet basic securityrequirements specified by XML Advanced Electronic Signatures (XAdES).Further, since the design of the illustrative embodiments is based onXML signatures, (XAdES) requirements such as the addition of anauthenticated timestamp to the signature are inherently supported.

With reference to FIG. 9, a code snippet example of a manifest, inaccordance with the disclosure is presented. In terms of signaturevalidation, an important aspect of the design of the example embodimentbases the composite resource document format on ODF packaging, whichmeans that one of the resources in the composite resource document is amanifest listing all resources. Manifest 900 provides a list of allresources within the composite resource document. Resources in manifest900 such as loan1.xhtml, loan2.xhtml and loan3.xhml provide astep-by-step user interface for collecting information that is placed inthe data resource loanInstance.xml. Other files like gen-default.css andformat.js contribute to the user interface appearance and run-timebehaviors of the composite resource document.

With reference to FIG. 10, a code snippet example of XML data in acomposite resource document template, in accordance with variousembodiments of the disclosure is presented. In the example, when adocument template is first instantiated to drive a specific businessprocess on behalf of a user seeking a loan, the initial content ofloanInstance.xml is as shown in the code snippet of FIG. 10.

In code snippet 1000 the initial configuration of the <ds:Signature>element, element 1002, does not include any <Reference> elements.Reference elements are absent because the disclosed design imparts asubtraction semantic on the XML signature Reference list, which meansthat the resources listed in the manifest will be included automaticallyat the time of signature generation and checked automatically at thetime of validation.

With reference to FIG. 11, a code snippet example of XML Data in afilled composite resource document of FIG. 10, in accordance withvarious embodiments of the disclosure is presented. Once the usercompletes the data fill experience using loan*.xhtml, the data will looklike code snippet 1100. Data values now populate previously emptytemplate fields 1102.

With reference to FIG. 12, a code snippet example containing a compositeresource document signature definition, in accordance with variousembodiments of the disclosure is presented. Code snippet 1200 representsa completed document having a set of references, manifest and digitalsignature using information from FIG. 9, FIG. 10 and FIG. 11.

When a user invokes the Sign operation, as provided in element 1002 ofFIG. 10 the disclosed process adds the same document reference forloanInstance.xml, for example element 1202, in which URI=“ ” enablingthe signature being generated to be omitted from itself and addsreference elements for all other resources listed in the manifest, suchas reference 1204, reference 1206 and reference 1208. A reference forthe manifest.xml file, manifest 1210, is also added.

The digital SignatureValue of element 1212 is also depicted. Element1212 illustrates the content of the signed info portion of the compositeresource document definition before the core digital signaturegeneration operation, which produces the content of the SignatureValueelement after the disclosed process generates the Reference elements.

A signature validation operation ensures unwanted file additions ordeletions have not occurred by validating the reference to themanifest.xml. An assumption that the ODF package document processor willnot load a document when there is a conflict between the manifest andthe actual archive content is also made. An alternate implementation maysimply check for reference and manifest parity at the time of signaturevalidation.

In another example, a grant application in which two or more grantapplicants are expected to fill out respective personal information,attach a copy of a curriculum vitae, digitally sign the document and letthe workflow system send the document to the next applicant forcompletion is presented. A digital signature created by the first usermust subtract data file sub-trees corresponding to other applicants andattachments created by other applicants. Other than the two previousexceptions, all other files in the composite resource document describethe user interface, the user experience, or the data or attachments forthe signing user, and hence all should be signed.

The arbitrary ability to attach files allows more XHTML pages, CSSfiles, JS files and so forth to be placed into the composite documentresource. Further, since the content.xml file is omitted because thecontent.xml file contains control structures such as “which xhtml pageshould be shown first”, any newly added files could possibly add newalternative user experiences that could make false claims with respectto what the first signer signed. The possibility of making false claimsis prevented by taking the notion of subtraction filtering up to theReference list level of an XML signature.

With reference to FIG. 13, a code snippet example of a compositeresource document signature definition illustrating reference listgeneration, in accordance with various embodiments of the disclosure ispresented. The zero case of subtraction filtering provided by variousembodiments of this disclosure is an important change of behaviorrelative to prior art. By default an XML signature requires anapplication designer to use Reference elements to list resources to besigned. In a composite resource document, the application designercreates a template and typically decides to include a digital signaturefeature. However, at run-time, an end-user may need to modify aninstance of the template created to drive a business process. Anexpected end-user operation attaches new files into the compositeresource document. Thus, it is not possible at application design timeto list as Reference elements all of the resources that must be signedat the run-time moment of signature generation. Instead, it is necessaryfor the enhanced signature generator of the composite resource documentprocessor to create the list of Reference elements at the time thedigital signature is generated.

Therefore, it is important to augment the signing operation with a stepthat generates a Reference element generator for each resource in thecomposite resource document, including the manifest. This is the case ofsubtracting zero of the resources in the composite resource documentfrom the signature. Code snippets of FIG. 10, FIG. 11 and FIG. 12 showedan example of this case in which zero files were subtracted. However,the text only showed markup immediately before the signature generationprocess and immediately after the full signature generation process. Theprevious examples did not show the intermediate markup at the pointafter the digital signature augmentation that generates the Referencelist and before the core digital signature generation. FIG. 13 providesan additional markup sample as code snippet 1300. Element 1302 defines aSignature element and element 1304 defines one of the Reference elementsautomatically generated by various embodiments of the disclosed process.

A set of reference elements, including element 1304 was generated intothe SignedInfo, and each has an empty DigestValue element. As well theSignature Value is also empty. After the previously described signingaugmentation, further steps can occur before core signature generationincluding for example, a step that adds a ds: Object to include basicsignature properties such as signing time and locale, and anotherreference to sign. In another example, ds:KeyInfo would be added tostore the digital signing certificate and subject name of the signer. Afurther Reference can be automatically added to sign the KeyInfo, aswell. Ultimately, the core digital signature generator is invoked toproduce the DigestValue content and the Signature Value content. Anexample of the final result of enhanced signature generation is shown inthe markup example of code snippet 1200 of FIG. 12.

With reference to FIG. 14, a code snippet example of a compositeresource document definition having multiple signers and illustrating ameans of specifying the transformed resources, in accordance withvarious embodiments of the disclosure is presented. As described abovefor FIG. 13, there is value in treating the XML signature reference listas a subtraction filter that subtracts zero elements by default. Forexample, the Reference list is generated programmatically as anaugmentation to the signing operation rather than beforehand by anapplication designer (the creator of the template of the compositeresource document). Thus, the disclosed capability enablesimplementation of a process to sign the whole document when the documentis a composite resource document, in particular when end-users can addmore resources to the document than were available in the originaldocument template.

Moreover, the disclosed process adds auto-generated references towhatever Reference elements are already provided, enabling theapplication designer, the creator of the template for the compositeresource document, to elect to sign information in addition to what isgenerates by the disclosed process. For example, application logic maygenerate information into a ds: Object in the signature, and thesignature may be configured with a reference to sign the ds: Object.

Most importantly, the disclosed process merges the auto-generatedReference element list with a Reference element list in the SignedInfo,effectively adding a Reference for each resource only if it does notalready have a pre-existing Reference in the SignedInfo. When animplementation of the disclosed process does add a Reference, theReference results in signing the whole resource, so the disclosedprocess is responsive to any Transforms applied to specific resources byan application designer or alternative aspects of the composite resourcedocument processor.

In an example, a “loan” application previously described is designed tosatisfy a signer-cosigner scenario. The data in a loanInstance.xml fileis represented in code snippet 1400. A first Signature 1402 is providedas well as a second Signature 1404. The signature of second signer 1404is identical in form to the signature of the earlier examples, but firstsigner 1402 already contains a Reference to URI=“ ” that subtracts notonly itself (the enveloped signature) but also the signature of thesecond signer, which must be generated after the first signature isaffixed. Hence, when the disclosed process generates Reference elementsfor first signer 1402, the URI=“ ” Reference is not generated because italready exists.

With reference to FIG. 15, a code snippet example of specifying apattern to control reference generation, in accordance with variousembodiments of the disclosure is presented. The material in previousexample code snippets describe a first step of a subtraction filter, inwhich a default context of signing everything available is used, ratherthan signing only what is explicitly listed. Fully enabling subtractionfiltering at the composite resource document level allows theapplication designer to specify by pattern which additional Referencesshould not be generated when using the disclosed process.

In previous examples, wildcard regular expression syntax was used, butan XPath expression may also be used. In this example a signature isaffixed enabling subsequent additions of files into the compositeresource document, but only in a specific directory, such as anattachments directory. The markup of code snippet 1500 provides anexample in which element 1502 specifies the explicit pattern forresource subtraction, which in this example matches all resources in an‘attachments’ subdirectory into which a user is therefore permitted toadd or delete resource attachments.

With reference to FIG. 16, a code snippet example of filtering specificresources from the generated signature reference list therebysuppressing the reference generation for the specific resources using anobject of FIG. 15, in accordance with various embodiments of thedisclosure is presented. The disclosed process, in response to theobject defined in code snippet 1502 of FIG. 15 adds a Reference to thespecial ds:Object so that the signature signs the filter, amends themanifest.xml Reference to subtract file-entry elements that match thedescriptor and suppresses generation of Reference elements for resourcesthat match the descriptor provided.

Another example using code snippet 1600 filters files from a stylesubdirectory, due to the resource descriptor of element 1602.

The generated URI=“ ” Reference element receives elements 1604, asubtraction transform for the signature and a union for the resourcedescriptor object. Reference elements having URI attributes that beginwith style/ do not appear in the list. A Reference to manifest.xml,element 1606, receives a subtraction filter that omits file-entryelements matching the description.

With reference to FIG. 17 a flowchart of a process of generating adigital signature for a composite resource in accordance with thedisclosure is presented. Process 1700 is an example of a process usingcomposite document system 500 of FIG. 5.

Process 1700 starts (step 1702) and receives a composite resourcedocument containing at least one resource (step 1704). Process 1700obtains an updated manifest resource, wherein the manifest resourcelists all resources in the composite resource document (step 1706).Process 1700 indicates zero, one or a plurality of resources to subtractfrom the list of resources in the updated manifest resource to create agenerated signature reference list of identified resources to be signed(step 1708). Identify now refers to the resources being signed, and doesnot include the resources being removed. In an embodiment, generatingthe generated signature reference list further comprises including areference that indicates an object, wherein the object declares a listof resource descriptions indicating a list of resources subtracted fromthe resource list to create the reference list.

Process 1700 generates a hash token using the resources identified inthe generated signature reference list to form a signature hash token(step 1710). In an embodiment, generation of the hash token includesselection of one or a plurality of resources in the reference list toform selected transformed resources, wherein remaining resources fromthe reference list form untransformed resources, and applying digitalsignature transforms to the selected transformed resources to generatethe hash token using the untransformed resources combined with theselected transformed resources. In particular, an embodiment thatconforms to the current W3C XML Signatures standard analyzes theSignature SignedInfo element for preexisting Reference elements whoseURI attributes indicate resources in the reference list, and theembodiment only generates Reference elements for reference listresources that do not correspond to any of the preexisting Referenceelements. Thus, each preexisting Reference element, which may contain aTransforms element, overrides the Reference element that would otherwisebe generated for the resource in step 1708, and this resultant list ofReference elements from this process is used in step 1710 to generatethe signature hash token.

In an embodiment, generating a signature hash token may further compriseat least one of using a URI resolver to obtain the content of one or aplurality of resources in the reference list and generating thesignature hash token using the digest value of at least one of theresources in the reference list. In particular, an embodiment thatconforms to the current W3C XML Signatures standard calculates theSignatureValue hash token based on the digest values, rather than theactual content, of all of the resources in the reference list.

Process 1700 encrypts the signature hash token with a secret key tocreate a digital signature (step 1712) and terminates thereafter (step1714).

With reference to FIG. 18 a flowchart of a process of validating thedigital signature for a composite resource of FIG. 17 in accordance withthe disclosure is presented. Process 1800 is an example of a processusing composite document system 500 of FIG. 5.

Process 1800 starts (step 1802) and receives a composite resourcedocument, containing one or a plurality of resources, having a digitalsignature (step 1804). Process 1800 obtains an updated manifestresource, wherein the updated manifest resource lists all resources inthe composite resource document (step 1806).

Process 1800 generates a hash token using the resources identified inthe generated signature reference list in the digital signature to forma generated hash token (step 1808). Process 1800 decrypts an encryptedhash token contained within the digital signature using an obtaineddecryption key to form a signature hash token (step 1810). Responsive toat least a comparison of the generated hash token and the signature hashtoken, process 1800 generates a signature validity result (step 1812)and terminates thereafter (step 1814).

With reference to FIG. 19 a flowchart of a process of generating asignature validity result of FIG. 18 in accordance with the disclosureis presented. Process 1900 is an example of a process comparing agenerated resource hash token and a decrypted digital signature hashtoken in step 1814 and generating a signature validity result in step1816 of FIG. 18.

Process 1900 begins (step 1902) and determines whether the generatedhash token is equal to the signature hash token (step 1904). When adetermination is made that the generated hash token is equal to thesignature hash token, a “yes” result is obtained. When a determinationis made that the generated hash token is not equal to the decrypteddigital signature hash token, a “no” result is obtained. When a “no”result is obtained, process 1900 generates an invalid signature validityresult (step 1906) and terminates thereafter (step 1908). Thedetermination further comprises determining whether a list of resourcesfrom the updated manifest resource is not equal to a list of resourcesidentified in the generated signature reference list in the digitalsignature. In an embodiment, the list of resources from the updatedmanifest resource comprises a list of resources from the updatedmanifest resource less those resources indicated by an object thatdeclares a list of resource descriptions indicating a list of resourcessubtracted when forming the generated signature reference list.

When a “yes” result is obtained in step 1904, process 1900 determineswhether the decryption key is valid (step 1910). When a determination ismade that the decryption key is valid, a “yes” result is obtained. Whena determination is made that the decryption key is not valid, a “no”result is obtained. A determination of whether the decryption key isvalid includes testing validity of the decryption key using zero, one ora plurality of tests including a key expiry test, a key revocation test,a key issuer credential test and a trusted key list test. Responsive toa failure of a decryption key validity test, a signature validity resultof invalid is generated.

When a “yes” is obtained in step 1910, process 1900 responds to theoverall determination that the generated hash token is equal to thesignature hash token and no failures of decryption key validity tests bygenerating a signature validity result of valid (step 1912) andterminates thereafter (step 1908). The determination further comprisesdetermining whether a list of resources from the updated manifestresource is equal to a list of resources identified in the generatedsignature reference list in the digital signature. In an embodiment, thelist of resources from the updated manifest resource comprises the listof resources from the updated manifest resource less those resourcesindicated by an object that declares a list of resource descriptionsindicating a list of resources subtracted when forming the generatedsignature reference list. When a “no” result is obtained in step 1910,process 1900 generates a signature validity result of invalid (step1906) and terminates thereafter (step 1908) as before.

Thus is presented in an embodiment computer-implemented process forcreating a digital signature for a composite resource document thatprovides high security in digital signatures for composite resourcedocuments by providing a resource subtraction filter capability absentfrom previous solutions for digitally signing multiple resources. Thedisclosed computer-implemented process receives the composite resourcedocument containing at least one resource, obtains an updated manifestresource, wherein the updated manifest resource lists all resources inthe composite resource document, indicates zero, one or a plurality ofresources to subtract from the list of resources in the updated manifestresource to create a generated signature reference list of identifiedresources to be signed, generates a hash token using the resourcesidentified in the generated signature reference list to form a signaturehash token and encrypts the signature hash token with a secret key.

Generating the hash token may also include forming the reference listusing previously specified reference elements for zero, one or aplurality of the resources, thereby enabling a capability to attachdigital signature transforms to the processing of the resourcesindicated by the previously specified references elements.

Illustrative embodiments of the computer-implemented process furtherprovide a capability of validating a digital signature for a compositeresource document. The computer-implemented process further receives thecomposite resource document, containing one or a plurality of resources,having a digital signature, obtains an updated manifest resource,wherein the updated manifest resource lists all resources in thecomposite resource document, generates a hash token using the resourcesidentified in a generated signature reference list in the digitalsignature to form a generated hash token, decrypts an encrypted hashtoken contained within the digital signature using an obtaineddecryption key to form a signature hash token and responsive to at leasta comparison of the generated hash token and the signature hash token,generates a signature validity result.

Thus, illustrative embodiments disclose a composite resource documentusing a compressed archive and in which separate resources within theone document represent data records, attachments, pages and additionalelements. The composite resource document retains the advantages ofsingle document architecture while eliminating the need to perform XMLparsing of the entire archive to obtain pieces needed to provide thepage-by-page user experience. Support of multiple references toresources offered by the Worldwide web Consortium (W3C) XML signaturesenables W3C XML signatures to be used in conjunction with compositeresource documents to implement a digital signing function. However, thesubtraction filtering capability is not limited to the processing ofsingle XML resources. For a higher level of defining multiple resourcesto be simultaneously signed, the W3C XML signatures standard currentlyprovides only a listing capability, specifically the list of resourcesobtained from the list of Reference elements in the Signature SignedInfoelement.

Known prior solutions typically have drawbacks for digitally signing aninteractive document including representing a document as a single XMLfile, which allows subtraction filtering but has poor performance, andrepresentation of the document as a composite resource, which offersbetter performance but does not allow resource-level subtractionfiltering.

A disclosed process combines the notion of a composite resource documentwith subtraction filtering to achieve a same level of digital signaturesecurity on composite resource documents in collaborative businessprocesses while also achieving a significant advancement in performanceoffered by composite resource documents.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

While the invention has been described with reference to one or morespecific embodiments, the description is intended to be illustrative ofthe invention as a whole and is not to be construed as limiting theinvention to the embodiments shown. It is appreciated that variousmodifications may occur to those skilled in the art that, while notspecifically shown herein, are nevertheless within the true spirit andscope of the invention.

What is claimed is:
 1. A method comprising: receiving a compositeresource document, containing one or more resources, having a digitalsignature; obtaining an updated manifest resource, wherein the updatedmanifest resource lists all resources in the composite resourcedocument; generating a hash token using the resources identified in agenerated signature reference list in the digital signature to form agenerated hash token; decrypting an encrypted hash token containedwithin the digital signature using an obtained decryption key to form asignature hash token; and responsive to at least a comparison of thegenerated hash token and the signature hash token, generating asignature validity result, which comprises: responsive to adetermination that the generated hash token is not equal to thesignature hash token, generating a signature validity result of invalid,wherein the determination further comprises determining whether a listof resources from the updated manifest resource is not equal to a listof resources identified in the generated signature reference list in thedigital signature; and testing validity of the obtained decryption keyusing zero, one or a plurality of tests including a key expiry test, akey revocation test, a key issuer credential test and a trusted key listtest.
 2. The method of claim 1, wherein the composite resource documentcontains a plurality of resources.
 3. The method of claim 1, whereingenerating a signature validity result further comprises: responsive toa failure of a decryption key validity test, generating a signaturevalidity result of invalid; and responsive to a determination that thegenerated hash token is equal to the signature hash token and absent afailure of the decryption key validity test, generating a signaturevalidity result of valid, wherein the determination further comprisesdetermining whether a list of resources from the updated manifestresource is equal to a list of resources identified in the generatedsignature reference list in the digital signature.
 4. The method ofclaim 1, wherein generating a hash token using the resources identifiedin the generated signature reference list further comprises: using a URIresolver to obtain the content of one or more resources identified inthe generated signature reference list.
 5. The method of claim 1,wherein generating a hash token using the resources identified in thegenerated signature reference list further comprises: performing atleast one digital signature transform on at least one of the resourcesidentified in the generated signature reference list.
 6. The method ofclaim 1, wherein generating a hash token using the resources identifiedin the generated signature reference list further comprises: generatingthe hash token using a digest value of at least one of the resourcesidentified in the generated signature reference list.
 7. The method ofclaim 1, wherein the composite resource document is a digital documentcomprising a plurality of discrete resources, which selectively have acorresponding digital signature unique to that resource.
 8. An apparatuscomprising: a communications fabric; a memory connected to thecommunications fabric, wherein the memory contains computer executableprogram code; a communications unit connected to the communicationsfabric; an input/output unit connected to the communications fabric; anda processor unit connected to the communications fabric, wherein theprocessor unit executes the computer executable program code to directthe apparatus to: receive a composite resource document, containing oneor more resources, having a digital signature; obtain an updatedmanifest resource, wherein the updated manifest resource lists allresources in the composite resource document; generate a hash tokenusing the resources identified in a generated signature reference listin the digital signature to form a generated hash token: decrypt anencrypted hash token contained within the digital signature using anobtained decryption key to form a signature hash token; and responsiveto at least a comparison of the generated hash token and the signaturehash token, generate a signature validity result, which comprises:responsive to a determination that the generated hash token is not equalto the signature hash token, generating a signature validity result ofinvalid, wherein the determination further comprises determining whethera list of resources from the updated manifest resource is not equal to alist of resources identified in the generated signature reference listin the digital signature; and testing validity of the obtaineddecryption key using zero, one or a plurality of tests including a keyexpiry test, a key revocation test, a key issuer credential test and atrusted key list test.
 9. The apparatus of claim 8, wherein directingthe apparatus to generate a hash token using the resources identified inthe generated signature reference list further comprises directing theapparatus to: generate the hash token using a digest value of at leastone of the resources identified in the generated signature referencelist.
 10. The apparatus of claim 8, wherein the composite resourcedocument is a digital document comprising a plurality of discreteresources, which selectively have a corresponding digital signatureunique to that resource.
 11. A non-transitory computer readable storagemedium having computer usable program code embodied therewith, thecomputer usable program code comprising: computer usable program codeconfigured to: receive a composite resource document, containing one ormore resources, having a digital signature; obtain an updated manifestresource, wherein the updated manifest resource lists all resources inthe composite resource document; generate a hash token using theresources identified in a generated signature reference list in thedigital signature to form a generated hash token; decrypt an encryptedhash token contained within the digital signature using an obtaineddecryption key to form a signature hash token; and responsive to atleast a comparison of the generated hash token and the signature hashtoken, generate a signature validity result, which comprises: responsiveto a determination that the generated hash token is not equal to thesignature hash token, generating a signature validity result of invalid,wherein the determination further comprises determining whether a listof resources from the updated manifest resource is not equal to a listof resources identified in the generated signature reference list in thedigital signature; and testing validity of the obtained decryption keyusing zero, one or a plurality of tests including a key expiry test, akey revocation test, a key issuer credential test and a trusted key listtest.
 12. The non-transitory computer readable storage medium of claim11, wherein the computer usable program code to direct the apparatus togenerate a hash token using the resources identified in the generatedsignature reference list further comprises computer usable program codeto: generate the hash token using a digest value of at least one of theresources identified in the generated signature reference list.
 13. Thenon-transitory computer readable storage medium of claim 11, wherein thecomposite resource document is a digital document comprising a pluralityof discrete resources, which selectively have a corresponding digitalsignature unique to that resource.
 14. A method comprising: receiving acomposite resource document, containing one or more resources, having adigital signature; obtaining an updated manifest resource, wherein theupdated manifest resource lists all resources in the composite resourcedocument; generating a hash token using the resources identified in agenerated signature reference list in the digital signature to form agenerated hash token; decrypting an encrypted hash token containedwithin the digital signature using an obtained decryption key to form asignature hash token; and responsive to at least a comparison of thegenerated hash token and the signature hash token, generating asignature validity result, which comprises: responsive to adetermination that the generated hash token is not equal to thesignature hash token, generating a signature validity result of invalid,wherein the determination further comprises determining whether a listof resources from the updated manifest resource is not equal to a listof resources identified in the generated signature reference list in thedigital signature; responsive to a failure of a decryption key validitytest, generating a signature validity result of invalid; and responsiveto a determination that the generated hash token is equal to thesignature hash token and absent a failure of the decryption key validitytest, generating a signature validity result of valid, wherein thedetermination further comprises determining whether a list of resourcesfrom the updated manifest resource is equal to a list of resourcesidentified in the generated signature reference list in the digitalsignature.
 15. The method of claim 14, wherein the composite resourcedocument contains a plurality of resources.
 16. The method of claim 14,wherein generating a signature validity result further comprises testingvalidity of the obtained decryption key using zero, one or a pluralityof tests including a key expiry test, a key revocation test, a keyissuer credential test and a trusted key list test.
 17. The method ofclaim 14, wherein generating a hash token using the resources identifiedin the generated signature reference list further comprises: using a URIresolver to obtain the content of one or more resources identified inthe generated signature reference list.
 18. The method of claim 14,wherein generating a hash token using the resources identified in thegenerated signature reference list further comprises: performing atleast one digital signature transform on at least one of the resourcesidentified in the generated signature reference list.
 19. The method ofclaim 14, wherein generating a hash token using the resources identifiedin the generated signature reference list further comprises: generatingthe hash token using a digest value of at least one of the resourcesidentified in the generated signature reference list.
 20. The method ofclaim 14, wherein the composite resource document is a digital documentcomprising a plurality of discrete resources, which selectively have acorresponding digital signature unique to that resource.